<!DOCTYPE html>
<html>
<head>
    <title>Logical Not Example 1</title>
    <script type="text/javascript">
    
        alert(!false);      //true
        alert(!"blue");     //false
        alert(!0);          //true
        alert(!NaN);        //true
        alert(!"");         //true
        alert(!12345);      //false

    </script>

</head>
<body>
  
</body>
</html>